Gear pump unit



May 19, 1959 l A. s. JoHNsoN 2,887,065

' GEAR PUMP UNIT Filed Dee. 7, 195e 2 sheets-sheet 1 A. S. JOHNSON GEARPUMP UNIT May 19, 1959 2 Sheets-Sheet 2 Filed Dec. 7, 1956 if iff/Zim@United States Patent O GEAR PUMP UNIT Arthur S. Johnson, Providence,R.I. asslgnor to Brown & Sharpe Mfg. Co., Providence, RJ., a corporationof Rhode Island Application December 7, 1956, Serial No. 626,865

Claims. `(Cl. 10S-126) The present invention relates to a pressure uidgear pump, and is concerned more particularly with an improvedconstruction and method of assembly of an external gear pump unit.

It is an object of the invention to provide a novel and improved gearpump which is simple, requires for its construction a minimum number offinished surfaces, and is readily assembled into an efficientself-contained unit.

It is a further object of the invention to provide a novel and improvedintegrally formed housing having formed therein bores to receive theseveral operating parts of an external gear pump, said bores being welladapted to provide an efficiently formed andsimply shaped `pumpingchamber and liuid passa-ges for said pump.

It is another object of the invention to provide a novel method ofassembling an external gear pump unit of which the operating parts aresupported within a single housing provided with two gear receiving boresentering the casing from opposite ends with their axes spaced apart adistance equal to the spacing between the centers of the meshing gearsso that the two bores cut into one another radially `and project pastone another by an amount equal to the length of the pumping chamber inwhich said gears are received. t

With the above and other objects inview as may hereinafter appear `theseveral `features of the invention consist in the devices, combinationsand arrangement of the parts and in the method hereinafter described andclaimed which, together with the advantages to be obtained thereby, willbe readily understood by oneskilled inthe art from the followingdescription taken in connection with the accompanying drawings,inwhich-f- Fig. 1 is a side view of an external gear pump embodying theseveral features of the present invention,` the casing being sectionedto show the pump `gears and their supporting arbors; t.

Fig. 2 is an end view ofthe pump shown in Fig. 1 looking from the right,the gear mechanism and the bores in which this mechanism is `housedbeing shown in dotted lines; t

Fig. 3 is a sectional view in elevation taken on line 3--3 ofFig.l; -w rN Fig. 4 is a sectionalview in elevation takenlon line 4--4 of Fig. 1,and; y

Figs. 5, 6 and 7` are sectionalviews similar to Fig. 1 illustrating themethod of assembly of the gear mechanism in the housing; in which- Fig.5 shows the upper gear, its supporting bushing and arbor, the bushingand gear engaged thereby being seated against the finished inner end ofthe bore;

Fig. 6 shows the` additional assembly of the lower gear and itssupporting bushing which has been pushed inwardly so that the lower gearsseated at the end of its bore to the right;`and

Fig. 7 is a linal assembly view `in which the arbor for the upper gearhas been pushed inwardly again forcing the upper gear to the left whileleaving the supportingbushl another by a substantial amount.

` tion of the bushing 62.

2,887,065 Patented May 19, 1959 2 ing in thepposition determined by itsengagement with the lower gear.

The external gear pump here disclosed as embodying in a preferred formthe several features of the invention comprises an integrally casthousing 10 having formed therein two parallel bores 12 and 14 which formthe entire receiving chamber for the moving parts of the gear pump. Theupper bore 12 projects into the casing from the right hand end as viewedfor example in Figs. 1, 5, 6 and 7, terminating at its inner end in afinished surface 16. There is also provided a further axial extension ofthe bore 12 in the form of a hole 18 which provides a bearing supportfor the inner end of the upper driving gear arbor hereinafter described.The lower bore 14 projects into the casing from the left hand end asviewed in Figs. l, 5, 6 and 7, terminating in a finished surface 20. Afurther axial extension 22 of the bore 14 provides a bearing support forthe lower gear arbor hereinafter described. It may be noted that the endof the hole 22 is extended through the right hand end of the casing,being normallyy closed by means of a screw threaded plug 24.

The diameters of the respective bores 12 and 14 are chosen to receivethe respective upper and lower gears 26 and 28 of the pumping unit withan additional allowance for clearance which may, for example, amount tobetween .001 and .O02 inch. The axes of the two bores are further chosento coincide with the axes of the two gears 26 and 28 when properlymeshed.

As will be readily evident from inspection of the drawings, the twobores 12 and 14 are projected past one Further the bores are suiicientlylarge to overlap or cut into one another. The bores with theirrespective finished end surfaces 16 and 20 extend past one another by anamount which is exactly equal to `the axial dimension of each of the twogears with a small additional amount provided for necessary clearance.

The housing 10 is also formed, as best shown in Figs. 2 and "3, with adat base 30, with a transverse inlet port 32 and with a transverseoutlet port 34 leading respectively to and from the gear chamber abovedescribed, which may be generally designated at 36.

The upper gear 26 is fixedly mounted on a gear arbor 33 which, whenassembled in the gear unit, as best shown` a sleeve bearing 42 mountedin a bushing 44 which serves as a plug for the open end of bore 12.

The bushing 44 is rigidly secured in its adjusted position by means of atransverse pin or dowel 46 which is driven into a hole in the housing 10and in the bushing 44. A water-tight fit between the bushing and therotating arbor is effected by means of a gland which comprises a packing48 mounted in an annular recess in the outer end of bushing 44, and aflanged sleeve member 40 which is forced tightly against the packing 48by means of screws 52 seated in the flanged portion of sleeve 50 andthreaded into the end of bushing 44. A liquidtight tit between bushing44 and housing lll is provided by means of anO-ring 54 mounted in anannular groove `in the outer periphery of `bushing 44. The lower gear 2Sof thepumping unit is rigidly secured p to an arbor 56 which is mountedat its left hand end as best shown in Fig. l in a sleeve bearing 58provided in a hole 6i) formed in a bushing 62 which is utilized to plugthe open end of the bore 14. Adjacent its other end the arbor 56 issupported in a sleeve bearing 64 mounted in the hole 22 in the housing.The bushing 62 is secured to its adjusted position by means of atransverse pin or dowel 66 which is driven ing through thehousing Aliquid-tight fit is provided beinto a hole pass- 10 and through theupper porp aesaoas 3 tween the bushing 62 and thev housing 10 by meansof an O-ring 68 mounted in an external. annular groove in the bushing62.

Further in accordance with the invention applicant provides a novelmethod of assembling the moving parts of his external gear pump in theimproved and. simplied housing above set forth. The method by means ofwhich the pump unit is assembled comprises the following steps.

The bearing 40 is initially assembled in housing; l0 and bearing 42 in.bushing 44'. The upper driving gear 2.6l and the arbor 38 to which it isrigidly secured are then assembled with the bushing44, the O-ring 54 andthe sleeve 50. These parts are then insertedv into the upper bore 12 ofthe housing from the right hand end, pressure being brought specificallyagainst the bushing 44 which acts against the adjacent face of gear 26..The gear 26 is thus driven into the bore until it is engaged firmlyagainst the finished end surface 16 of the bore, as specifically shownin Fig. 5. Bearing 64 is assembled in housing 1t), and bearingv 58 inbushing 62. The lower driving gear 28 of the unit together with thearbor 56 to which it is rigidly secured are similarly assembled with.the bushing 62, the assembled parts then. being inserted into the lowerbore 14 of the housing from the left hand end. Pressure is broughtspecifically against the bushing 62 which acts against the adjacent faceof gear 28 so that the gear 28 is moved to the right until its. rests.firmly against n the finished surface 20 forming the inner end of thelower bore 14. During the movement of the gear 28 to the right the gearwill be brought into engagement with a lower portion of bushing 44 andwill, cause the bushing to be retracted so that the inner end face ofthe bushing 44 is flush with the nished surface 20 of the inner end ofbore 14. inasmuch as, the bushing 44 is now located in its finalposition of adjustment, pin 46 is driven home thus locking the bushing44 in position in the housing. During the inward movement of the bush--ing 62 and gear 28 above described, the bushing 62 will move slightlybeyond the end face 16 of the bore 12 so that the bushing 62 will engageand move the gear 26 to the right, this being the position of thepartsispecifically shown in Fig. 6.

The next step in the assembly operation consists in the. forcing of thearbor 38 and driving gear 26 of the upper gear unit to the left so thatthe inner face of the gear 26 is again brought into contact with the endsurface 16 of the bore 12. During this operation the inner face of thelgear` 26 is also brought. into engagement with the inner face of thebushing 62 which is again forced outwardly until the inner face of thebushing. 62 isbrought iiush with the face 16 of the bore 12. Thisrepresents the finally adjusted position of. the bushing` 62.which isnow locked in said position by the insertion of the dowel 66.

In the event that it is necessary to dis-assemble the unit the two pinsor dowels 46 and 66 are driven out, thus releasing the respectivebushings 44 and 62. The plug 24 is Withdrawn and a suitable tool isinserted. to drive the lower gear unit out of the lower bore 14. Asuitable tool may then be inserted into the lower bore against theadjacent face of the gear 26 which is then driven out of the upper boretogether with the associated parts of the upper gear assembly.

The invention having been described what is claimed is:

l. An external gear pump unit which comprises a driving gear and itssupporting arbor, a driven gear and its supporting arbor, said drivingand driven gears being of the same length, a one-piece housing havingformed therein two parallel bores entering and extending only partiallythrough the housing from opposite ends, of which they axes of'said borescoincide with the axesof the respective gears when meshed, the diametersof therespectivcl bores are the outside diameters of the respectivegears with a/small allowance added for clearance, said bores beingprojected past one another by an amount. equal to the length of therespective gears with a small allowance added for clearance, each ofsaid. bores having. a finished inner end face, thus providing a gearchamber having the circumferential contours and length of said chamberaccurately determined in accordance with the diameters and lengths ofsaid gears, holes in said housing forming axial extensions of therespective hores to provide support for the respective arbors, bushingslocated in said housing having the'outside diameters gauged to closesaid bores and inner end faces finished to provide end faces for thegears in' said chamber and drilled to provide supports for therespective gear arbors, and means for pinning each bushing to thehousing in an axially adjusted position inv the` respectivebore: in`which said finished face of each bushing is fiusht with said finishedinner end face of the adjacent parallel bore..

2. An external gear pump unitin accordance with claim l in which thedriving gear with its supporting arbor andxthe` driven gear with its'vsupporting arbor are formed as integral one piece units;

3. AnY external gear pump unit ntaccordance with claim 1 in which thatportion of the supporting. arbor for the driving. gear. through which.the drive is taken is mounted in the associated bushingand alubricantpressure sealing device is connected between4 said. driving arbor andsaid associated bushing for sealingluid under pressure within the pumpchamber.

4. The method of assembling an external. gear pump unit having a drivinggear, a driven gear, a driving arbor to which the. driving gear. is`fixed, and a driven arbor on which said driven gear is supported, aonepiece housing with two parallel bores of sutiiciently large diameterto receive said. gears entering the' housing from opposite ends alongthev rotational' ax'esl of said gears when meshed, and an. arbor.supporting bushing closing the open end of' each of said. bores; saidbores havin-g the end faces thereoffprojeeted past one another' to forma gear chamber within the housing, the length of said. chamber beingaccurately-f determined to receive said gears, which method compri'sesfthe steps of projecting the driving arbor, the driving gear andassociated bushing into one of said bores, exertingpressure against thebushing to push the driving gear against the endface of the bore,thereafterv projecting the driven arbor, the associated driven gear and'bushingk into the other one of saidbores, exerting pressure against saidlatter bushing to force the driven gearf against the end face of thesaidy second bore and at the. 'samer time said driven gear engaging andretracting saidV driving gear bushing flush with said end face of thesecond. bore, and thereafter advancing the driving arbor and gearindependently of the associated bushing against thel end: facev of thefirst mentioned bore, and atA thesame time vsaid driving gea-r engagingand retracting said driven arbor bushing flush with the end of5the-driving gea-r supportingl bore.

5. The method of; assembling" an` external gear pump runit having adriving gear, a driven gear, a driving arbor to which the driving gearis fixed, and a driven arbor on which said driven gear issupported, aone-piece housing with two parallel bores of sufficiently large diameterto receive said :gears entering the housing from opposite ends along therotational axes of said gears when meshed, and an arborsupportingbushingclosing' the openV end of each of said bores', saidA bores havingthe end faces thereof projected past one anotherv to form a gearcharnber within the housing, tliel'ength. of said chamber beingaccurately determined to receive` said gears, whichk methodcomprises'the steps of projecting the driving arbor. the-driving gear.and. associated? bushing into one ofsaid bores, exertingpressure-'againsty thel bushing to push the drivingvgear againstthe endfacemf thebore, thereafter projecting the driven arbor, the driven gear and,supporting.l bushing into. the otherof.- said bores, exerting pressure.against the latter bushingv to force the drivenr gear against theendface vof saidsecond bore.` while the latter @,aagoes 5 6 bushingpushes against and retracts the driving gear and the end face of thedriving arbor supporting bore, and

the driven gear engages 4and retracts the driving bushing securing thelatter gear bushing in position in the housing. Hush with the end faceof the latter bushing, securing References Cited in the le of this:patent the rst mentioned bushmg m position 1n the housing,

thereafter advancing the driving arbor and driving gear 5 UNITED STATESPATENTS against -the end face of the bore while the driving gear1,682,793 Moorhouse Sept. 4, 1928 engages and retracts the driven arborbushing ush with 2,236,980 Unger Apr. 1, 1941

